1. Field of the Invention
The present invention relates generally to wires for use in medical procedures. More specifically, the present invention relates to guidewires and hostwires capable of being converted from an over-the-wire length to a rapid-exchange length.
2. Description of the Prior Art
Guidewires are generally elongate structures for use in medical procedures. During such procedures, a distal portion of the wire is positioned within a lumen of a patient's body to acquire and/or maintain access to a treatment site. Commonly, such a lumen of a patient's body includes a stenosed region at a location in the patient's vascular system. A catheter can be advanced over a wire for treatment or diagnostic purposes.
The wire and catheter are positioned within the patient's body by an operator such as a medical doctor. A proximal portion of the wire and a proximal portion of the catheter extend outwardly from the patient's body for manipulation by the operator. In the case of over-the-wire systems, at least a portion of the wire must extend proximally relative to the proximal end of the catheter, thereby allowing the catheter to be manipulated axially relative to the wire.
Distal protection devices are devices that protect tissue downstream in a patient's vascular system from emboli arising during medical procedures. Distal protection devices may be filters or may be occlusive, and are deployed distal to a treatment site. The filter or occlusive element is mounted to a hostwire. Hostwires have some functions similar to guidewires in that catheters are commonly advanced over both to or near treatment sites.
Guidewires and hostwires may be maintained at an intended axial position within the lumen of the patient's body so as to afford access to a treatment site, as desired. The wire may be maintained by any means that enable the relative position of the wire to be established within the lumen, such as by an anchored distal protection device, or by manually maintaining the position of the wire within the lumen. Once an axial position is established, the wire is maintained in position to allow treatment and diagnostic devices such as a percutaneous transluminal coronary angioplasty (hereinafter referred to as “PTCA”) balloon catheter, a stent, or the like to be advanced over the wire to the treatment site.
During a procedure, the operator must be able, when necessary, to manipulate the catheter and wire relative to each other. Thus, as previously discussed, for over the wire systems, the wire must have a greater length than the receiving lumen of the catheter in order for the operator to be able to maintain access to the wire independently of the catheter during catheter exchanges. Typically, these wires are over 300 cm in length.
Two types of wire/catheter configurations are commonly employed: an “over-the-wire” configuration and a “rapid-exchange” configuration. In an “over-the-wire” configuration, the wire is used with an over-the-wire catheter comprising an elongate body having a lumen extending the length of the catheter. The over-the-wire catheter is advanced relative to the wire by sliding the wire through the lumen. Again, in order for the operator to position the over-the-wire catheter with respect to the wire, a portion of the wire must extend from the patient's body and out of the proximal end of the over-the-wire catheter.
A rapid-exchange catheter has an elongate structure, only a distal portion of which defines a used region having a receiving lumen for receiving the wire. The receiving lumen of a rapid-exchange catheter is typically considerably less than half the overall length of the rapid-exchange catheter. Thus, the wire, in order to extend from the patient's body, need only be longer than the appropriate length of the receiving lumen of the rapid-exchange catheter and the length of the vascular passage from a point of body ingress to a port in the catheter through which the wire enters the receiving lumen. Typically, these wires are about 175 cm in length. The operator is, therefore, able to manipulate the catheter with respect to the wire with a much shorter wire length. The result is that the length of the wire in a rapid-exchange configuration can be significantly less than the length of an over-the-wire wire.
During the course of a procedure, a plurality of devices may be advanced over the wire. The devices may be for use in an over-the-wire configuration or a rapid-exchange configuration. An over-the-wire system configuration generally provides more support to the catheter and has superior lesion crossing abilities, especially in tortuous anatomy. A rapid-exchange catheter is generally easier for the operator to use and may require less assistance during operation relative to an over-the-wire catheter. The length of the wire, again, depends on the type of catheter configuration that will be employed. It is not, however, always known in advance whether an over-the-wire length or a rapid-exchange length wire will be required.
Because of the possibility that a combination of rapid-exchange and over-the-wire length catheters will need to be employed, rapid-exchange length guidewires that are extendable to an over-the-wire length for receiving over-the-wire length catheters have come to be employed.
The superior crossing ability of over-the-wire systems coupled with the ease of use of a rapid-exchange guidewire or hostwire, however, makes it beneficial to have an over-the-wire length guidewire or hostwire that can be transformed into a guidewire or hostwire capable of use in a rapid-exchange configuration. A convertible wire would allow the operator to position and anchor the wire within a lumen of a patient's vasculature using an over-the-wire catheter and then convert the wire to a rapid-exchange length, as needed, for use with rapid-exchange catheters during the same procedure. This would eliminate the need for the manufacture of separate wire assemblies for use with rapid-exchange catheters and over-the-wire catheters.